Expose isMutableSource() from AbstractField and integrate with MetadataPlugin [moved]

[jonnybbb]

This is Issue 4 moved from a Google Code project.
Added by 2009-11-13T01:21:49.000Z by andrew.pietsch.
Please review that bug for more context and additional comments, but update this bug.

Original labels: Type-Enhancement, Priority-Medium

Original description

Current there's no way for plugins to determine if fields are backed by a
mutable value model.

Will need to add public static method
MetadataPlugin.initialiseMetadataBindings(FormModel) to handle the case
where none of the enable(...) disable(...) are used.